NEW HANOVER — The state has decided the best solution for residents with contaminated wells along routes 663 and 73 is to extend a $2 million water line from Superior Water Company to provide public water to those homes.

The state has estimated it will take about one year to complete the project, but no start date was included in the document outlining the decision.

According to the “Statement of Decision,” issued March 1 by the Pennsylvania Department of Environmental Protection, constructing the water line is a “feasible, implementable, effective and permanent solution to the threat of exposure to site-related contaminants through ingestion, inhalation of groundwater.”

The decision follows a December public hearing at Boyertown Junior High School East during which the alternatives available to the DEP were mapped out, and the public offered input and asked questions.

The state has focused on the former Swann Oil Co., at 334 Layfield Road, as the likely source of the contamination, a site whose contamination history dates back to the early 1970s. It was also the site of the former Good Oil Co.

The latest investigation was kick-started in July 2011, when a test on a well at 326 Layfield Road found high levels of contaminants, including those from a family of chemicals known as volatile organic compounds, or VOCs.

In January 2012, samples on 12 shallow wells on the property showed contaminants in eight of them.

Last April, monitoring wells were installed around the perimeter of the property to try to track the direction in which the contamination is moving.

• Trichloroethylene, or TCE — an increasingly common industrial pollutant which found in the wells at levels ranging from 15 to 624 parts per billion, between three times and 125 times the safety level established by the Environmental Protection Agency.

• DCE, or cis-1,2-dichloroethene — which was found at levels 25 to 1,580 parts per billion, as much as 22 times the safety level established by the EPA.

• Vinyl chloride — one of the few chemicals recognized by the federal government as a carcinogen which was found at levels ranging from 10 to 100 parts per billion, between five and 50 times the EPA standard.

In addition to risks from drinking the water, there may also be health risks associated with inhaling the solvents, which can become airborne during a shower.

DEP spokeswoman Lynda Rebarchak suggested “taking shorter showers” for those with contaminated wells, as well as “cracking a window” and running a ventilation fan.

The investigation of the underground plume of contamination is continuing but, as Ragesh Patel, manager of the the Southeast Regional DEP’s Hazardous Sites Cleanup Program, said during the December hearing, getting a reliable supply of clean water to those whose wells are polluted and are now using in-house filtration systems and bottled water is the department’s first priority.

Although hook-up to the system would be free, residents would face monthly water bills from Superior from that point onward, DEP spokeswoman Lynda Rebarchak said in December.

In an email to The Mercury in December, Superior Water Co. President Louise Knight wrote, “Our average customer uses less than 50,000 gallons annually, yielding an average bill of about $7,000 per year.”

The water line option the DEP is recommending would also likely require a township ordinance governing the rules for hooking up to the system.

Some utilities require that once a water line passes in front of a home, the home be hooked up to the system, whether its well is polluted or not.

It would be up to the New Hanover Board of Supervisors to set those rules, Rebarchak said.

Residents would have to attend the public hearing on that ordinance to have input on how those rules work, she said, adding that the DEP would recommend against those rules allowing polluted well water to be used outside, where it might get on garden vegetables and pose a health risk.

Those whose wells are contaminated, and have been using bottled water for more than a year, would be hooked up to the system at the state’s cost.

The state would also pay the hook-up costs for any additional area homes that were found to have contaminated water during the year it is anticipated it would take to extend the water line.

The state will pick up the cost of the cleanup for those area residents who were not initially offered the opportunity to hook up to the system, but whose wells subsequently show chemical levels exceeding those considered safe, according to the DEP.